Motor Driver Circuit Self-Turn-On Prevention via Gate Control
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Solution Overview
Problem
Existing motor driver technologies experience abnormal conditions such as self-turn-on due to abrupt voltage changes in H-bridge circuits, leading to wasteful consumption currents and reliability issues.
Innovation Solution
A circuit device with a bridge circuit, pre-driver circuit, and control circuit that includes switch circuits and a level shifter, where the control circuit manages the switch circuits to prevent self-turn-on by setting the gate nodes to appropriate voltage levels during voltage changes, and using high-voltage transistors for the bridge circuit and low-voltage transistors for other circuits to reduce layout area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a transistor gate node is left floating during voltage switching in an H-bridge circuit, then the circuit structure remains simple, but self-turn-on occurs causing wasteful consumption current and reliability issues
Solution Approach 1:
The patent applies preliminary action by proactively setting the gate node voltage to an appropriate level before abrupt voltage changes occur in the H-bridge circuit. The control circuit monitors the switching state and preemptively adjusts the gate voltage to prevent self-turn-on, rather than reacting after the problem occurs. This prevents wasteful consumption current while maintaining circuit simplicity.
2Reliability
If high-voltage transistors are used throughout the circuit, then voltage change protection is improved, but layout area increases
Solution Approach 1:
The patent applies local quality by using high-voltage transistors only in specific locations where they are most needed (in the H-bridge circuit subject to abrupt voltage changes) while using low-voltage transistors in other parts of the circuit where high voltage protection is not required. This selective approach maintains voltage change protection where critical while minimizing overall layout area.
3Reliability
If the gate node voltage is actively controlled during switching, then self-turn-on is prevented improving reliability, but control complexity increases
Solution Approach 1:
The patent applies feedback by implementing a control circuit that monitors the switching state of the H-bridge and automatically adjusts the gate node voltage accordingly. The control circuit receives feedback about voltage changes and responds by setting the gate voltage to appropriate levels, creating a closed-loop system that prevents self-turn-on while keeping the control logic relatively simple through systematic feedback mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents or reduces self-turn-on occurrences and wasteful consumption currents, improving the reliability and efficiency of the motor driver by effectively managing voltage changes and optimizing transistor usage.
Implementation Method 1
a gate capacitance (gate-drain capacitance) is present in a transistor for driving. It has been therefore found that, when an abrupt voltage change occurs at a node of a terminal of the motor, this voltage change is conveyed to the gate node of the transistor for driving via the gate capacitance
Data Source
AI summary
When a counter-electromotive force generated by an inductive load is applied to the drain of a switch element, the gate of the switching element may pull the gate potential toward the direction opposite to its original potential due to capacitance coupling of the drain-gate capacitance, and this may cause a malfunction. To cope with this, a switch element that pulls the potential to the reverse direction is provided and controlled to turn on at timing at which the counter-electromotive force is applied.